Method of applying barrier coatings to glass panels

ABSTRACT

An index-matching coating is applied directly to a low-emissivity (“lowE”) thin-film coating. Nodules growing from a site in the lowE coating are removed to avoid propagation of defects through the layers of the index-matching coating. A tempering step in an oxygen-containing atmosphere produces compressive stress in the lowE coating and hardens the coating. The compressive stress facilitates removal of the nodules and the hardening allows mechanical cleaning of the lowE coating prior to the index-matching coating, further removing nodules. Magnesium-fluoride is used as the final layer of the index-matching coating in one embodiment to improve abrasion resistance. The resulting glass panel may be used as a display panel in a plasma display or an organic light-emitting diode display, for example.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional patent application of commonlyowned, U.S. patent application Ser. No. 09/990,195 entitled GLASS PANELWITH BARRIER COATING AND RELATED METHODS, by Brad A. Duffy and Robert W:Adair, filed Nov. 21, 2001, now U.S. Pat. No. 6,703,373, the disclosureof which is hereby incorporated in its entirety for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates generally to improving the environmentaldurability of coated glass panels that are used in displays and similarapplications, and more particularly to a coated glass panel that hasbeen treated to remove particles before backfilling the voids left bythe particles with an overcoat material.

Glass panels are used in a wide variety of display technology. Displaysthat can use glass panels include television sets, computer screens, andinstrument panels, to name a few. The glass panels are often coated orotherwise treated to improve the performance characteristics or meet aspecified requirement of the display. For example, a panel might beslightly etched to reduce reflectivity, or an anti-reflective film orcoating might be applied to the front and/or back surface of the glasspanel.

Films or coatings might be applied in a variety of ways. One approachapplies a self-adhesive sheet of polyethylene terephthalate (“PET”) to aglass panel. The PET sheet may be coated itself, such as with ananti-reflective (“AR”) coating. The AR coating is typically a layer orlayers of materials that improve the optical match between the PET andthe air. Other techniques deposit a layer or layers of material directlyonto the surface of the glass panel.

Some display products generate electro-magnetic interference (“EMI”),and glass panels used in such displays might be treated to reduce theEMI radiated from the panel into the environment, particularly toward auser. In some instances, a fine wire mesh is attached to or imbedded ina glass panel assembly to reduce emissions. The wire mesh is typicallygrounded through a wire. Such an assembly can be expensive and reducethe clarity or resolution of the display. Another approach has been todeposit a low-emissivity (“lowE”) coating onto the surface of the glasspanel. LowE coatings have been developed by, and are available from, anumber of suppliers and often contain silver, copper, or goldincorporated into a layer or layers of the coating. LowE coatingstypically have better than 45% transmission in the visible spectrum anda sheet resistivity of less than 5 Ohms per square, and in someinstances have a sheet resistivity of about 0.5 Ohms per square.

Unfortunately, lowE coatings are often moisture sensitive, and moistureintrusion can induce corrosion in the coating layers. In particular,humidity can infiltrate the low-E coating and cause “blooms” to appear,which degrade the appearance of the panel. Moisture typicallyinfiltrates through a defect in the coated layers. Several techniquesaddress reducing the formation of defects, and other techniques havebeen developed to seal the defects. One approach is to attach a sheet ofPET to the lowE coating with pressure-sensitive adhesive to seal thedefects. The relatively thick PET layer protects the lowE coating fromenvironmental moisture. The front surface of the PET sheet is coated toreduce reflections in some instances, typically in a roll coater beforethe PET sheet is applied to the glass.

However, using such a polymer sheet increases the number of componentsand assembly steps required for the glass panels. This in turn increasescosts and decreases product yield and mechanical durability.

Therefore, a glass panel that can provide EMI shielding, high clarity,and that is resistant to moisture-induced corrosion is desirable.

BRIEF SUMMARY OF THE INVENTION

A thin-film barrier overcoat is deposited directly over amoisture-sensitive coating on a glass panel to provide environmentalprotection to the moisture-sensitive coating. In a particularembodiment, the moisture-sensitive coating contains a metallic layer,such as are common in lowE coatings. In a further embodiment, thebarrier overcoat is an AR coating. Nodules, which otherwise mightpropagate defects through the thin-film barrier overcoat, have beenremoved from the lowE coating prior to the barrier overcoat depositionprocess. In one embodiment, the panel is tempered in anoxygen-containing atmosphere to facilitate the removal of nodules and toharden the lowE coating sufficiently for mechanical cleaning. Othercoatings might not be tempered or need hardening to facilitate removalof the nodules. In a particular embodiment, the final thin-film layer ofthe barrier overcoat is a low-friction material, such as MgF₂. A secondAR coating can be applied to the other surface of the glass to enhancethe transmission of light through the panel from a display such as aplasma display, or that surface of the glass might support a device suchas an organic light-emitting diode.

In another embodiment, a polymer sheet is attached to the surface of theglass substrate, which can be tempered or untempered, on the sideopposite the lowE and AR coatings. A second AR coating can be applied tothe polymer sheet before it is attached to the glass.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified tracing of a micrograph illustrating a defect ina coated glass panel.

FIG. 2A is a simplified tracing of a scanning electron micrograph of across section of a portion of a coated glass panel.

FIG. 2B is a simplified cross section of the coated glass panel of FIG.2A with nodules removed to form pinholes according to an embodiment ofthe present invention.

FIG. 2C is a simplified cross section of the coated glass panel with abarrier overcoat according to an embodiment of the present invention.

FIG. 3 is a simplified graph of the predicted reflectivity of aconductive coating stack with and without an index-matching coating.

FIG. 4 is a simplified cross section of a glass panel coated accordingto an embodiment of the present invention.

FIG. 5 is a simplified cross section of a coated glass panel with anorganic light-emitting diode according to another embodiment of thepresent invention.

FIG. 6 is a simplified cross section of a glass panel coated accordingto yet another embodiment of the present invention.

FIG. 7 is a simplified cross section of a glass panel coated accordingto yet another embodiment of the present invention.

FIG. 8 is a simplified flow chart of a process for fabricating a coatedpanel according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A coated glass panel is treated to remove nodules that could become asource of moisture intrusion or other contamination. The panel is thentreated with an overcoat layer to seal, and in some cases fill orpartially fill, the voids left by the removed nodules. In oneembodiment, the coating on the glass panel is a lowE coating thatincludes one or more layers of silver-containing material. The coatedglass panel can be used in a display panel application, such as for aplasma display or an organic light-emitting diode display, and istypically rectangular and several centimeters to a few meters on anedge, although other configurations and sizes are possible. In otherembodiments, the moisture-sensitive coating is opaque, such as a mirrorcoating.

FIG. 1 is a simplified tracing of a micrograph illustrating a defect ina coated glass panel 10. Moisture has entered a pinhole 12 in thecoating and has migrated through silver layer or layers in the coating,corroding those layers. The corrosion appears as a bright “bloom” 14 inthe otherwise clear field 16 of the coated glass panel. Pinholes can bevarious sizes, i.e. diameters at the surface of the coating, but aregenerally in the range of 1-1000 microns. Larger pinholes degrade theoptical quality of the coating even without moisture intrusion andcorrosion. Pinholes that are sufficiently small resist moistureintrusion. In a particular application, most pinholes were between 5-40microns, with the upper limit being consistent with the desired visualquality of the coated part.

FIG. 2A is a simplified tracing of a scanning electron micrograph of across section of a portion of a coated glass panel 20 illustratingnodules. A lowE coating 22 has been formed on a glass substrate 24. Theglass substrate could be pane of “window glass”, tempered glass, opticalglass, laminated glass, or similar material, such as plastic panels andfilms suitable for the intended processing steps and quality of thefinished part. LowE coatings are typically eight to fifteen layers thickwith silver, silver alloy, or copper conductive layers 26, 28 surroundedby protective layers 30, 32, 34 of materials such as ZnO, TiO₂, Si₃N₄,SiO₂, Nb₂O₅ and others.

There are typically 3-5 conductive layers, with the sheet resistivity ofeach layer contributing to the overall sheet resistivity of the coating.Other designs may have more or less conductive layers. The conductivelayers are sufficiently thin to transmit light, yet are sufficientlyconductive to suppress electromagnetic emissions through the coating.The sheet resistances of the conductive layers vary from 50 ohms/sq downto less that 1.5 ohms/sq with visible transmission ranging from about95% down to about 45% across the visible spectrum. Such coatings will bereferred to as “transparent” for purposes of discussion, even thoughsome transmission loss occurs and even though such coatings might not beequally transmissive throughout the visible spectrum. The protectivelayers are relatively moisture resistant and protect the metal layersfrom corrosion induced by moisture. The layers in the lowE coating arerelatively thin and are typically deposited in a single vacuum step.

The conductive layers are typically grounded through a buss bar formedat the perimeter of the panel assembly. The buss bar can be of a silverfrit, for example, and provides a reliable electrical contact to theconductive layers of the lowE coating. Other types of electricalcontacts can be used to connect to the lowE coating.

Nodules 36, 38, 40 have formed in the lowE stack. A nodule 40 can growfrom a defect site 42 on the substrate or within the thin film stack asa result of coating spatter or other external contaminants. Variouschanges in stress, such as a change in temperature of the thin filmstack during processing or in use, can cause some nodules to loosen andfall out, resulting in pinholes 43. Even if nodules remain in thecoating, moisture can travel down the boundary 44 of the nodule-coatinginterface and cause corrosion in the conductive layers.

FIG. 2B is a simplified cross section of the coated glass panel 20illustrated in FIG. 2A with the nodules removed to form pinholes 46, 48according to an embodiment of the present invention. While some mayrefer to defects in the coating as “pinholes” whether or not the noduleis present in the defect, for the purposes of this discussion the term“pinhole” refers to a defect from which a nodule has been removed, thusleaving a void. The process of removing the nodules will be discussed infurther detail below.

FIG. 2C is a simplified cross section of the coated glass panel 20illustrated in FIG. 2B with a barrier overcoat according to anembodiment of the present invention. The pinholes have been sealed witha barrier overcoat 50. Some pinholes are essentially filled withovercoat material, while other pinholes might only be partially filledor basically sealed at the surface of the coating. The coating can be alowE coating, or other coating that has layers that are sensitive tomoisture-induced corrosion. The thickness of the barrier overcoat is notshown to scale, and the conformation of the barrier overcoat to thecoating on the glass panel is merely exemplary. For example, a moreviscous barrier overcoat may penetrate the pinholes less than a lessviscous overcoat.

In a particular embodiment, a lowE coating includes several layers ofvarious materials, including conductive layers 26, 28 and protectivelayers 30, 32, 34. The barrier overcoat may or may not seal the edges52, 54 of the conductive layers exposed in the pinholes. The barrierovercoat may be additional vacuum-deposited thin film layers or may be achemical layer, such as a perfluorosilane, that is sprayed, spun,evaporated, or otherwise applied to the surface of the coated glasspanel. In one embodiment the barrier overcoat is an adhesive layerbetween the coated glass panel and a sheet of PET. In a furtherembodiment, the adhesive layer includes a dye to color-shift the outputof the glass panel assembly.

In another embodiment the barrier overcoat is a series ofvacuum-deposited thin films. In a particular embodiment, the series ofvacuum-deposited thin films is selected to match the refractive indexbetween the lowE or other coating on the glass panel and air. In oneexample, a lowE coating commonly known as Q4™, available from CARDINALCG, of Tumwater, Wash. The reflection reducing coating included a 5.25nm thick layer of titanium/praseodymium oxide, a 84.62 nm layer of MgF₂,a 86.82 nm layer of titanium/praseodymium oxide, a 25 nm layer ofindium-tin oxide, and a 63.36 nm layer of MgF₂, which interfaces withthe air. The index-matching stack is deposited directly on the lowEcoating stack. In another embodiment, the first and third layers areitanium dioxide layers. In other embodiments, other metal oxide layerscould be used. The exact materials and thicknesses of the index-matchingovercoat varies according to the type of coating being matched(overcoated), and many different combinations of materials andcombinations might solve any given index-matching system. The coatingmight be index-matched to air or the adhesive layer of apressure-applied polymer film, for example, among other media. Othertypes of moisture-sensitve coatings would generally be index matchedusing a different thin-film stack, as is known in the art of ARcoatings.

FIG. 3 is a simplified graph 60 of the predicted reflectivity of a Q4™conductive coating stack with 62 and without 64 the index-matching stackdescribed in the preceding paragraph. This model was conducted withwhite light in an air medium, with the coatings on a glass substrate andan ideal detector. A 15-degree angle of incidence was assumed.

Experimental data shows that unprotected lowE-type coatings might notconsistently pass the 20-rub eraser abrasion test. With an overcoatprocess that provides an MgF₂ layer as the top layer, a glass panel willconsistently pass a 40-rub eraser abrasion test. It is believed that thecoefficient of friction of the surface of the panel is modified by theMgF₂, which is relatively smooth and offers a lower coefficient offriction on the surface.

FIG. 4 is a simplified cross section of a glass panel 70 coatedaccording to an embodiment of the present invention. A glass substrate22 is coated with a lowE coating 24 and a barrier overcoat 76. The glasssubstrate can be tempered to improve the breaking strength of the glassand further improve safety by reducing the size of the glass pieces thatmight result from fracturing the panel. Glass tempering is generally aprocess that heats the glass and then rapidly cools the glass, whichputs the surface of the glass into compression, thus resisting breakage.The tempering process can also create compressive stress in the lowEcoating. Tempering can be achieved in a number of different atmospheresand at a number of different temperatures. In some embodiments, it maybe desirable to not alter the tempering of the glass, such as when theglass substrate is strongly tempered before coating, yet remove nodulesor harden the coating through a heat treatment. For example, a longthermal soak in oxygen at a temperature below the softening point ofglass might retain the tempered characteristic of the substrate whilefacilitating removal of the nodules. In some embodiments, it isgenerally desirable to provide a heat treatment that producescompressive stress in the coating. It is not required that the coatingbecome compressed, as it is believed that a compressive change in thestress characteristic of the coating may facilitate the removal ofnodules.

The lowE coating has been processed to remove nodules, which allows thebarrier overcoat to seal the pinholes from moisture. In a particularembodiment the barrier overcoat is a stack of thin-film layers. In afurther embodiment, the upper most layer of the overcoat is alow-friction layer. The barrier overcoat stack can also index-match thelowE coating to the environment (typically air). An optionalanti-reflective (“AR”) coating 78 on the opposite side of the glasssubstrate may be desirable in applications, such as plasma displayscreens, where high total transmission of a broad spectrum of lightthrough the glass panel is desirable. The AR coating is designed toindex match the glass substrate to the ambient, which is typically airor other gas(es) inside the plasma display. In other words, the barrierovercoat faces the ambient environment, which in one embodiment is aplasma display and in another embodiment is an organic light-emittingdiode (“OLED”) display. Alternatively, the index-matching coating mayinterface with the ambient air in a room, or an adhesive layer of apressure-applied polymer sheet or other medium.

FIG. 5 is a simplified cross section of a portion of an OLED display 80according to another embodiment of the present invention. A glasssubstrate 24 has been coated on one side with a lowE coating 22 and abarrier overcoat 76. The other side of the glass panel includes a layerof transparent conductor 82, such as indium-tin oxide (“ITO”), an OLEDstructure 84, and a conductor layer 86, such as a patterned aluminumlayer. The OLED structure typically contains several layers, and issimplified here for purposes of illustration. Other layers of variousmaterials are typically present as well, and are omitted here forclarity of illustration.

The OLED structure is turned on by applying an electric signal betweenthe conductive layers, and emits light through the glass panel and outthe lowE coating and barrier overcoat. The lowE coating suppresses EMIfrom the OLED display, and is typically grounded through a perimetercontact bar, as with the plasma display panel described above inrelation to FIG. 2A. In an alternative embodiment, a glass panel with alowE and barrier overcoat may be used with an OLED display fabricated ona second substrate.

FIG. 6 is a simplified cross section of a glass panel assembly 80 coatedaccording to another embodiment of the present invention. A glasssubstrate 24, which can be untempered, tempered, or semi-tempered, hasan AR coating 78 on one side and a lowE coating 22 on the other. In apreferred embodiment, the lowE coating is processed to remove nodules.In one process, the glass substrate with the lowE coating is tempered.In a further process, the co-tempered glass substrate and lowE coatingis washed to further remove nodules. In other processes, the glasssubstrate is tempered before the lowE or other coating is applied. Inyet other embodiments, neither the glass substrate or the coating istempered, and other techniques are used to remove nodules.

A film of PET 82 with a layer of pressure-sensitive adhesive 86 andanother AR coating 84 is applied to the lowE coating 22. The PET filmprovides protection against breakage, and secures at least some of theglass shards in the event an untempered glass substrate breaks. It isbelieved that the combination of the AR coating directly on the backsideof the glass substrate and the PET film attached to the frontside of theassembly provides sufficient resistance against breakage and safety forsome applications. The terms “frontside” and “backside” are only usedfor convenient discussion and are not limiting for purposes of the glasspanel. Applying the AR coating directly to the backside avoids a secondapplication of AR-coated PET film, which could otherwise addconsiderable cost to the assembly, to achieve a high total transmissionof light through the panel.

In a further embodiment, the pressure-sensitive adhesive layer 86 isdyed to provide color-shifting or correction through the glass panelassembly 80. For example, the pressure-sensitive adhesive could be dyedto establish-color balance of a plasma display or tinted to correct orshift the output of an OLED. Alternatively, the PET film could betinted.

In a particular embodiment, the glass substrate 24 is tempered orsemi-tempered. The combination of such a glass substrate with a singlelayer of PET film 82 attached to the glass is particularly desirable forsafety reasons. If the tempered glass panel should break, it typicallybreaks into relatively small dice, rather than shards. It is believedthat the PET film will contain the dice in a safe manner more readilythan the shards that might be produced with an untempered glasssubstrate.

FIG. 7 is a simplified cross section of a glass panel assembly 90 coatedaccording to yet another embodiment of the present invention. A lowE orother coating 22 is formed on one side of the glass substrate 24, whichcould be untempered, semi-tempered, or tempered. The coating 22 has beenprocessed to remove nodules, which allows a barrier overcoat 76 to sealthe pinholes remaining after nodule removal from the environmentalmoisture. A PET film 82′ with a layer of pressure sensitive adhesive 86′has been applied to other side of the glass substrate. An optional ARcoating 84′ is applied to the PET film, typically before the film isapplied to the glass. Other types of adhesives, such as UV-curableadhesive, resin, and thermosetting adhesive may be used to attach othersorts of polymer films, such as polyester films, to glass panels. A dyemay be added to the adhesive layer 86′ or to the polymer film to colorshift or color balance the glass panel.

FIG. 8 is a simplified flow chart of a process 800 for fabricating acoated glass panel according to an embodiment of the present invention.A glass substrate was provided (step 801) and coated with amoisture-sensitive coating, which in one embodiment was a lowE coating(step 803), but other coatings may be used. The lowE coating was a Q4™that included silver-containing layers that transmit most light whileproviding shielding of at least some electro-magnetic emissions. Othercoatings, including other lowE coatings, could be used.

The Q4™ lowE coating was tempered by heating the glass substrate withthe lowE coating in an oxygen-containing atmosphere (e.g. air) to atemperature of 650° C. for about 90 seconds and then cooling in air inabout 30 seconds (step 805). This creates compressive stress in thecoating and helps to open pinholes by breaking the nodule defects freefrom the pinholes. The coating also becomes hardened through thetempering process. It is believed that at least some layers in theas-deposited lowE coating are further oxidized during the temperingprocess. That is, additional oxygen is incorporated into layers of thecoating to harden the coating and create the compressive stress. Theexact process parameters for tempering vary according to severalfactors. In one embodiment, the coating is hardened withoutsignificantly tempering the glass by heating the coated glass panel to alower temperature for a period of time sufficient for hardening of thecoating, and then slowly cooling the coated glass to avoid thermallyfracturing the glass.

The substrate and coating is then cleaned in a mechanical cleaningprocess (step 807). The cleaning process used high-pressure water anddetergent sprays to loosen remaining nodules. The nodules or otherartifacts were then swept away with a high-pressure water rinse or alight scrub with soft rotating brushes. The untempered lowE coating wastoo soft to withstand the mechanical cleaning without tempering, butother coatings may be robust enough to be mechanically cleaned to removenodules without the tempering step. An Al₂O₃ chemical barrier coating onglass, for example, might be durable enough to mechanically removenodules without tempering. With other coatings, such as front-surfacemirrors, nodules might be removed without tempering or washing byapplying a pressure-sensitive film with an adhesive that conforms to thesurface of the coating, and then removing the film and the nodules thatadhere to the adhesive.

Tempering may also be desirable to improve transmission and reduceresistivity of the lowE coating. In one instance, transmission improvedfrom about 68% to about 78% and sheet resistivity decreased from about4.3 Ohms per square to about 2.3 Ohms per square. The steps of temperingand washing 805, 807 are one embodiment of a step of removing nodulesfrom the moisture-sensitive coating. Other techniques for removal may beused, such as adhesive lift-off, blowing, vacuuming, or washing withouttempering, including brushless washing.

The coated substrate was then dried with a warm high-pressure air streamand loaded into a vacuum chamber for application of the barrier overcoat(step 809) before the moisture has time to attack the metal layers ofthe lowE coating. In this embodiment, it is believed that the vacuumpull-down aided the removal of water from the coating. The barrierovercoat was a thin-film AR stack designed to provide low reflectanceacross the visible spectrum. Removal of the nodules before depositingthe thin-film AR stack allows the AR stack to be deposited directly onthe lowE coating. Defects that would otherwise propagate through thethin-film AR stack are avoided by removal of the nodules, thus providingprotection of the lowE coating against moisture intrusion and allowingthe AR coating to serve as a barrier overcoat. The barrier overcoat doesnot have to be a thin-film AR stack, and could be other thin films or athick chemical (polymer) barrier overcoat, for example.

While the invention has been described above with respect to specificembodiments, other embodiments may be apparent to those with ordinaryskill in the art. Various details of the described embodiments of theinvention may be changed without departing from the spirit or scope ofthe invention. For example, although embodiments have been described inrelation to lowE coatings, which typically include metal-containinglayers that are susceptible to moisture intrusion, other coatings, suchas chemical barrier coatings may be used according to embodiments of theinvention. Therefore, the foregoing description of the embodiments ofthe invention is provided for the purpose of illustration only, and notfor the purpose of limiting the invention as defined by the appendedclaims and their equivalents.

1. A method of fabricating a glass panel, the method comprising:providing a glass substrate; depositing a moisture-sensitive coating ona first side of the glass substrate; removing nodules from themoisture-sensitive coating to form pinholes in the moisture-sensitivecoating; and sealing the pinholes.
 2. The method of claim 1 wherein themoisture-sensitive coating comprises a thin-film stack.
 3. The method ofclaim 2 wherein the thin-film stack is a lowE coating.
 4. The method ofclaim 1 wherein the removing step includes a tempering step and amechanical cleaning step.
 5. The method of claim 4 wherein themechanical cleaning step includes a high-pressure washing step and adrying step.
 6. The method of claim 5 wherein the mechanical cleaningstep further includes a brushing step before the drying step.
 7. Themethod of claim 2 wherein the removing step includes a tempering step ofheating the glass substrate and the thin-film stack to a temperature ofat least 650 degrees Celsius in an oxygen-containing atmosphere.
 8. Themethod of claim 2 further comprising, prior to the removing step, ofcreating a compressive stress in the thin-film stack.
 9. The method ofclaim 2 further comprising, prior to the removing step, of heating thethin-film stack to a temperature sufficient to add compressive stress inthe thin-film stack.
 10. The method of claim 1 wherein the sealing stepcomprises depositing a thin-film stack on the moisture-sensitivecoating.
 11. The method of claim 10 wherein the second thin-film stackis an index-matching stack.
 12. The method of claim 10 wherein thedepositing the second thin-film stack includes depositing an MgF₂ layeras an uppermost layer of the second thin-film stack.
 13. The method ofclaim 2 wherein the sealing step comprises applying an organic coatingon the thin-film stack.
 14. The method of claim 13 wherein the organiccoating comprises a pressure-sensitive adhesive.
 15. The method of claim13 wherein the organic coating comprises dye to color-shift the outputof the glass panel.
 16. The method of claim 1 further comprising a stepof applying a dyed layer to color shift the output of the glass panel.17. The method of claim 16 wherein the dyed layer is applied on a secondside of the glass substrate.
 18. The method of claim of claim 17 whereinthe dyed layer is an adhesive layer.
 19. The method of claim 17 whereinthe dyed layer is a polymer film layer.
 20. A method of fabricating aglass panel, the method comprising the ordered steps of: providing aglass substrate; depositing a lowE coating on a first side of the glasssubstrate; simultaneously tempering the glass substrate and the lowEcoating in an oxygen-containing atmosphere; mechanically cleaning thelowE coating; and, after cleaning the lowE coating depositing anindex-matching thin-film stack on the lowE coating.
 21. The method ofclaim 20 further comprising a step of depositing an anti-reflectivecoating on a second side of the glass substrate.
 22. The method of claim20 wherein the step of mechanically cleaning the lowE coating comprisesbrushing.
 23. The method of claim 20 further comprising a step ofapplying a dyed layer to color-shift the output of the glass panel. 24.The method of claim 23 wherein the dyed layer is applied on a secondside of the glass substrate.